Outline

Objective

Light emitting diodes (LED) offer the advantage of a stable luminance during the 'on' phase of the stimulus. The purpose of this study was to examine retinal function in a patient with MAR using a multifocal on- off-stimulation.

Methods

Retinal function was assessed with the panel D15 test, perimetry and the electroretinogram (ERG) according to ISCEV standard. A multifocal ERG (mfERG) (Retiscan™) was performed to elicit on- and off-responses with a LED stimulus screen (total stimulus length 200 ms, Filter setting: 10- 200 Hz) and compared to four control subjects. Responses of the mfERG were analyzed in 3 group averages: 1. The central 7.5 Â°, 2. 7.5-21.9Â° , 3. 21.9-32.1Â°.

Results

A 61-year-old woman with advanced metastatic non- pigmented melanoma of the vulva presented with night glare and painless photopsia as well as a temporal scotoma in her right eye. VA: 1.0 OU. IOP: 18mmHg OU. Retinal arteries were slightly narrower OU. OD showed a small flat naevus in the mid periphery. A blue-yellow error axis OD>OS was seen with the panel D15 test. Kinetic perimetry showed a concentric constriction of the visual field OD but was normal OS. The Ganzfeld ERG OD was consistent with MAR, showing a negative scotopic ERG. Oscillatory potentials were reduced and latencies of the flicker ERG were increased. The Ganzfeld ERG OS was normal. The mfERG on-response amplitude was reduced OU, whereby the central response averages were relatively more affected: Values were as follows: group 1. OD: 22.5 nV/deg2, OS: 8.6 nV/deg2 (n= 46.2-69 nV/deg2); group 2. OD: 11.9 nV/deg2, OS: 8,8 nV/deg2 (n= 24.0- 29.0 nV/deg2) and group 3. OD: 9.7, OS: 8.6 nV/deg2 (n= 20.0-25.0 nV/deg2). The off- response amplitude was also reduced (OD>OS), but to a lesser degree: group 1. OD: 13.8 nV/deg2, OS: 7.2 nV/deg2 (n= 19.9-28.7 nV/deg2); group 2. OD: 10.2 nV/deg2, OS: 4.0 nV/deg2 (n= 8.4-14.6 nV/deg2) and group 3. OD: 8,1, OS: 4.2 nV/deg2 (n= 9.0-12.8 nV/deg2). To take into account the variability in amplitude between recordings, we calculated the off/on-amplitude ratios: group 1. OD: 0.61, OS: 0.83 (n= 0.36-0.62); group 2. OD: 0.85, OS: 0.45 (n= 0.30-0.54) and group 3. OD: 0.83, OS: 0.48 (n= 0.4-0.59). These ratios show the right eye to be affected at all eccentricities, while the left eye has an abnormal off/on ratio only in the central 7.5Â°. Implicit times in either on- or off-responses did not differ from normal.

Conclusions

To our knowledge, this is the first report of multifocal on- off-responses elicited with LED in MAR. The resulting topography of on-off-responses holds the potential to increase our knowledge of the pathomechanism in MAR and allows a follow-up in these patients.